Field of the Invention
1. The present invention relates to a method for evaluating skin conditions and a kit for evaluating skin conditions.
2. Description of the Background Art
It is known that skin conditions has a close relationship to the barrier function of a horny layer, and the lowering of the barrier function brings on deterioration of the skin conditions, such as skin roughness. An amount of water volatilized out of the interior of the body through the skin (transepidermal water loss, TWL) is used as an index to such barrier function. It is said that TWL increases as the barrier function deteriorates. However, TWL is not always highly correlated with the barrier function of the horny layer. The reason for it is that the deterioration of the barrier function of the horny layer for stimuli and allergens is not grasped as the amount of substances penetrated into the interior from the exterior of the skin.
Accordingly, it is considered that the skin conditions can be exactly evaluated by determining the penetrability (percutaneous absorptivity) of substances into the skin. It is known that the penetrability of substances into the skin can be determined by the opto-coustic method, chromatographic method, absorptiometric ethod, etc.
However, the amount of a chemical substance penetrated into the skin varies according to factors such as the temperature and humidity of the chemical substance and skin, the amount of the chemical substance applied to the skin, and an application method, and it is technically difficult to conduct the measurement with such factors kept completely constant. Therefore, it has been extremely difficult to evaluate the skin conditions from the measured value of the penetrated amount, since an error in measurement is great. Accordingly, there has been a demand for development of a method for evaluating skin conditions, by which physiological skin conditions can be digitized.